The proposed project has several related objectives. First is to maintain a serum-bamk and cancer registry as a facility for studies of the epidemiology of major cancers, with special reference to serum factors antedating the diagnosis with serum assays of matched control specimens drawn at the same time, and also comparing serum assays of cancer cases before and after diagnosis which will identify risk factors, thereby adding useful knowledge of cancer etiology and helping to focus preventive practices. The second objective is to compare serum estrogen and androgen levels in serum specimens drawn in 1974 among breast cancer cases diagnosed since that time and their matched controls. The control experience will also be useful to see if serum hormone levels are related to other breast cancer risk factors. An additional study will measure disability and mood among breast cancer cases and age-matched controls. This will confirm and amplify a preliminary study that indicated that disability and mood changes among women several years after mastectomy resulted from age and not from their diagnosis or treatment. A fourth objective is to study serum estrogen and androgen levels among groups of postmenopausal women from a general population. Sufficient numbers of serum specimens can be examined to allow reasonably firm conclusions about normal levels in this cancer-prone age group and to relate these levels to a variety of personal characteristics. Finally, it is proposed to ascertain if there are long-term changes in a variety of serum hormone levels with storage at minus 70 degrees C. This information is not currently available and is badly needed not only for this study but also for other investigations that rely on frozen serum specimens.